This invention relates to the field of pressure forming or shaping of bodies, and more specifically, to an improved method which enables complex bodies to be made from a variety of materials such as metals, ceramics and plastics with minimal distortion, to near net shape, by utilization of a non-gaseous medium which transmits pressure applied by a simple press to the material being shaped.
Conventional metal forming techniques with which this invention will compete include such sheet metal forming techniques as press-brake forming, press forming, deep drawing, spinning, rubber pad forming, roll forming, stretch forming, hammer forming and explosive forming. All of these methods have found useful applications in the metals and plastics forming industries, yet, there are inherent limitations to all, as one can deduce from reading their summary descriptions in the "Metals Handbook Desk Top Edition." .sup.(1) The most important of these limitations include their inability to form non-symmetrical, closed surface (tube-like) complex shapes in most engineering alloy systems. More specifically, if an alloy system plastic deformation can only be achieved at elevated temperatures, or if the material system does not possess sufficient ductility at room temperature, most of these techniques are either useless or too cumbersome to be of practical use. FNT (1) American Society for Metal, ASM, Metals Park, Ohio 1985.
The present invention, on the other hand, allows not only the formation of non-symmetrical, closed surface complex shapes from nearly all metallic or plastic material systems, but it allows bonding of one material to another while forming one or both of the materials, thereby creating a composite, a more fully finished, useful part.
The key novelty in the present invention is the use of reusable solid particulate matter as the pressure transmitting medium. None of the existing techniques utilize particulate matter as the pressurizing medium. Furthermore, the types of particulate matter, hereinafter called grain, can be selected such that the forming operation can be performed at an elevated temperature without significantly damaging the pressure transmitting characteristics of the grain, or its reusability.